Contact-spring vibration damper



Jan.. M i927, ,613,66

G. R. LUM

A CONTACT SPRING yVIBRATION DAMPER Filed DSG. 15. 1920 9 mi A TI lll.

Patented Jaim-11, 1927.

Uiail'll STATES PATEN GEORGE R. LUM, OF NEW YORK, N. Y., ASSG-NOR TO "WESTERN ELECTBC COMANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATXON OF NEW YORK.

CONTACT-SPRING VIBRATION DAMPER.

Application filed December 13, 1920.

This invention relates to the use ofvibration absorbent means in connection with electrical Contact springs tor prevention of vibration otl said springs as they are brought into and out ot contact with cont-act blocks cooperable therewith The object of this invention is to provide means foretlectively prevent-ing the vibration ot electrical Contact springs upon being` brought into and out ot contact with Contact means ot' varying height.

ln adjustable electric circuits wherein the adjustment is controlled by the making or breaking of contacts usually between spring Contact members and contact blocks, it is inevitable that certain inequalities in level ot the successive contacting` surfaces must exist. ln passing over these inequalities, it the contact is a laterally sliding one or, in making or breaking contact il the motion is one ot frontal advance or receding, the contact springs normally are subjected to vibration ot an amount dependent on the degree ot inequality in successive surfaces encoun tered, the nature ot the contact material, and the stiffness of the springs. llllherever contacts are made and broken rapidly in a circuit containing a sensitive recording device such as an oscillagraph7 cathode ray tube, or telephone receiver held at the ear, it'or deterininations ot comparative performances oi ajiparatus, the vibration oit the Contact springs used in the adjustment mechanism j'nfoduces an oscillating effect in the minute arc formed on breaking the circuit and in the are that occasionally accompanies the cir- -cuit closure. This oscillation in the arc produces an uneven line in the visual tield of an oscillograph and cathode ray tube or a singing effect in the receiver. These effects are disturbing and, if their recurrence is rapid. malte the resultant visual or oral eiiects sought unintelligible.

To obviate the ditliculties above set fortln this invention provides means which may consist of felt or similar vibration absorbent material so situated adjacent contact springs as to prevent or greatly minimize their vibration upon being subjected to inequalities in surfaces contacting with them.

It is appreciated that use of means for .damping vibration of strings in musical in* struments is old in the art and such a combination is not contemplated in this invention but the damping means is here applied Serial No. 430,405.

to electrical contact springs to facilitate a prompt and complete make or break of cir cuit as the case may be without oscillation in the arc that may be produced.

The illustrative drawings disclose the damping means ot this invention applied to an electrical compensator switch such as may be used to electrically control compensation of time phase difference in electrical impulses transmitted over a plurality ot circuits. It is to be understood that drawings show but one application ot' this invention and do not define the limits thereot, reifer` ence being directed to the appended claims for this purpose.

F ig. l `discloses a vertical cross sectional view ot an electrical time phase compensator switch with iiXed contact springs and rotary connector blocks cooperable therewith. The spring` damping means ot' this invention is shown in contact with each spring.

Fig. 2 discloses an enlarged view oi a section ot the fixed portion of a compensator switch showing springs mounted thereon and vibration dampers in proper position.

Fig. 3 discloses a telephonie transmitter circuit for detection ot sound. vibrations and their conversion into electrical impulses, said circuit electromagnetically coupled through an electrical time phase con'ipenvsator ha'ving Contact springs and slidable connector blocks cooperative therewith, to a telephone receiver.

In detail, referring to Fig. l, there is disclosed a composite mounting of insulating material composed of a disk l and ring 9, contact springs 3 and 4 with bent-up ends 5 and 6, said ends being so adjusted as to bring a plane joining them parallel to the mounting plate l. An insulating plate 'i' on which are mounted connector blocks 8, said blocks being cooperable with contact springs 8 and 4, is retained in a plane parallel to spring mounting plate 1 by a stud shaft 9, and said insulating plate 7 is rotatable by means of a hand wheel l0. Pads ot resilient insulating material which may consist of felt or sott rubber, are disclosed in contact with the contact spring 3 and mounting l; also between springs 3 and 4l and in contact with them and the insulating ring 2, said pads for the purpose ot eliminating spring vibration when eri-- countering inequalities in the Contact sur face ol' connector blocks 8 or from these connector blocks into the spaces therebetween.

ln detail referring to Fig. 2, there is disclosed a part oi the saine structure as described in connection with Fig. 1 but enlarged so as to clearly show that the resilient insulating pads 11 and 12 substantially fill the spaces between adjacent sprii'igs and the composite insulating mounting 1, 2.

In detail, Fig. 3 discloses a telephonie transmitter 13 connected in series with a source of electrical energy 14 and the primary 15 of an' induction coil, said circuit for the purpose otl converting sound vibrations received by said transmitter into the corresponding electrical impulses. The secondary 16 ot said induction coil is connected through an electrical time phase compensator consisting ot series inductance 1T and shunt capacity 18 and switching means consisting ol an insulating plate 7 and connector blocks cooperating with contact springs 3 and el to adjust the amount of said compensator in circuit with a telephonie receiver 19. rlhe main purpose ol' the disclosure of Fig. 3 is to illustrate how vibration of the contact springs 3 and l would occur without the presence ot' the ribration damping means of this invention. A secondary purpose is to show where a switching means of the type described above may be used.

vWhat l claim is:

In an electrical switching mechanism, the combination ot a plurality ot' sets ot' flat contact springs each set comprising springs bent up at one end and arranged in a radial line and having their bent up ends in the same plane, a composite mounting of insulating material therefor, connectng blocks engageable with the bent up ends of said sets ot springs and attached to a rotatable insulating plate, and resilient insulating pads triangular' in shape in contact with the lower faces ot the springs of each set and with said mounting and approximately lilling the space between springs otl each set and said mounting.

ln witness whereof, l hereunto subscribe my naine this 9th day of December it. D., i920.

GEORGE R. LUM. 

